1. Field of the Invention
The present invention relates to an injection molding machine, more particularly to an injection molding machine having an injection chamber which is contoured to facilitate flow of liquid molding material therethrough.
2. Description of the Related Art
FIG. 1 illustrates a conventional injection molding machine which is shown to includes a machine body 1 mounted with an injection chamber unit 2, a screw barrel 4, mounted on the injection chamber unit 2, and an extruding screw 42 mounted inside the screw barrel 4. The injection chamber unit 2 is formed with a generally L-shaped injection chamber with a horizontal channel 21, a vertical channel 22 formed with an injection nozzle 221 at a bottom end thereof, an a transitioning passage 23 intercommunicating the horizontal channel 21 and the vertical channel 22. The screw barrel 4 is coupled to a drive mechanism, such as a hydraulic cylinder 43, and is driven by the hydraulic cylinder 43 to extend partially and movably into the horizontal channel 21 for reciprocating movement in the horizontal channel 21. As shown, when a liquid molding material flows from the horizontal channel 21 to the vertical channel 22, the route of the molding material turns almost at a right angle at the transitioning passage 23 so that the pressure and velocity of the material at the right angled part decrease to levels lower than the predetermined values thereof, thereby dramatically reducing the pressure of the material injected into the mold from the injection nozzle 221. In other words, the dead corner formed at the right angled part can generate a turbulent flow with considerable pressure drop, thereby accumulating the material at the right angled part and decreasing the efficiency of injection molding.
Therefore, the main object of the present invention is to provide an injection molding machine with an improved injection channel which can minimize or reduce the pressure drop occurring at a substantially right angled part thereof.
Accordingly, the injection molding machine of the present invention is used for injection molding a material, and includes a machine body, an injection chamber unit mounted on the machine body, a screw barrel mounted on the machine body and partially and movably extending into the injection chamber unit for reciprocating movement therein, and an extruding screw mounted inside the screw barrel. The injection chamber unit has a substantially horizontal channel for reciprocation of the screw barrel, a substantially vertical channel having an injection nozzle, and a transitioning passage interconnecting the horizontal channel and the vertical channel. The transitioning passage has an innermost turning side and an opposite outermost turning side longer than the innermost turning side. The transitioning passage includes at least two turning corners of obtuse angle at the outermost turning side. One of the turning corners is disposed at the juncture of the horizontal channel and the transitioning passage. The other one of the turning corners is disposed at the juncture of the transitioning passage and the vertical channel. The transitioning passage further includes an asymmetric tapered passage section which tapers toward the vertical channel and which has a wall part that partially confines the tapered passage section at the outermost turning side. The wall part has a shape conforming to a segment of a truncated cone-shaped face which extends angularly by an angle of less than 360 degrees.